OPC-UA Device Service

Overview

This repository is a Go-based EdgeX Foundry Device Service which uses OPC-UA protocol to interact with the devices or IoT objects.

Features

1. Subscribe/Unsubscribe one or more variables (writable configuration)
2. Execute read command
3. Execute write command
4. Execute method (using Read command of device SDK)

Prerequisites

• Edgex-go: core data, core command, core metadata
• OPCUA Server (Prosys Simulation Server, for example)

Predefined configuration

Simulation Server

Download the Prosys OPC UA Simulation Server from here. Install and run it to have access to the default configured resources.

Pre-defined Devices

Define devices for device-sdk to auto upload device profile and create device instance. Please modify devices.toml file found under the ./cmd/res/devices folder.

This device service is currently limited to a single device instance.

# Pre-define Devices
[[DeviceList]]
  Name = "SimulationServer"
  Profile = "OPCUA-Server"
  Description = "OPCUA device is created for test purpose"
  Labels = [ "test" ]
  [DeviceList.Protocols]
      [DeviceList.Protocols.opcua]
          Endpoint = "opc.tcp://127.0.0.1:53530/OPCUA/SimulationServer"

Configuration

Modify configuration.toml file found under the ./cmd/res folder if needed

# Driver configs
[OPCUAServer]
DeviceName = "SimulationServer"   # Name of existing Device
Policy = "None"                   # Security policy: None, Basic128Rsa15, Basic256, Basic256Sha256. Default: None
Mode = "None"                     # Security mode: None, Sign, SignAndEncrypt. Default: None
CertFile = ""                     # Path to cert.pem. Required for security mode/policy != None
KeyFile = ""                      # Path to private key.pem. Required for security mode/policy != None
  [OPCUAServer.Writable]
  Resources = "Counter,Random"    # Device resources related to Node IDs to subscribe to (comma-separated values)

Device Profile

A Device Profile can be thought of as a template of a type or classification of a Device.

Write a device profile for your own devices; define deviceResources and deviceCommands. Please refer to cmd/res/profiles/OpcuaServer.yaml.

Using Methods

OPC UA methods can be referenced in the device profile and called with a read command. An example of a method instance might look something like this:

deviceResources:
  -
    name: "SetDefaultsMethod"
    description: "Set all variables to their default values"
    properties:
      # Specifies the response value type
      valueType: "String"
      readWrite: "R"
    attributes:
      { methodId: "ns=5;s=Defaults", objectId: "ns=5;i=1111" }

deviceCommands:
  -
    name: "SetDefaults"
    isHidden: false
    readWrite: "R"
    resourceOperations:
      - { deviceResource: "SetDefaultsMethod" }

Notice that method calls require specifying the NodeId of both the method and its parent object.

The attributes field may also contain an inputMap: [] that passes parameters to the method, if applicable.

Build and Run

make build
cd cmd
EDGEX_SECURITY_SECRET_STORE=false ./device-opcua

Build a Container Image

make docker

Testing

Running unit tests starts a mock OPCUA server on port 48408.

The mock server defines the following attributes:

Variable Name	Type	Default Value	Writable
ro_bool	Boolean	True
rw_bool	Boolean	True	✅
ro_int32	Int32	5
rw_int32	Int32	5	✅
square	Method	Int64 (return value)

All attributes are defined in ns=2.

# Install requirements (if necessary)
python3 -m pip install opcua
# Run tests
make test

Reference

• EdgeX Foundry Services
• Go OPCUA library
• OPCUA Server